This application claims priority of Japanese Application No. 2001-227555 filed Jul. 27, 2001 and Japanese Application No. 2001-010343 filed Jan. 18, 2001.
1. Field of the Invention
The present invention relates to a method and apparatus for drawing an elongated stock continuously through different dies.
2. The Prior Art
Heretofore, there has been known an elongated stock drawing apparatus for causing the elongated stock to pass through a die for reduction to a predetermined diameter. Such a conventional drawing apparatus is shown in FIGS. 13 and 14, which are a front view and a side view, respectively, of the drawing apparatus. The elongated stock drawing apparatus includes, as components shown in FIG. 13, a base 50, dies 52 fixed onto the base 50, a first moving means 56 having a chuck 54 and adapted to reciprocate horizontally on the base 50, a swing means 62 with a rod 60 pivotally attached thereto, the rod 60 having a plug 58 at a front end thereof, a hydraulic cylinder 64 for moving the swing means 62 horizontally, the hydraulic cylinder 64 being fixed onto the base 50, and a holder 68 for holding an elongated stock 66 at a predetermined position, the holder 68 being provided above the base 50. The elongated stock 66 is in the shape of a cylinder, one end of which is formed with a flat portion 70 (flatwise crushed portion) as shown in FIG. 15.
The elongated stock drawing apparatus includes, as components shown in FIG. 14, and in addition to the above components, a lower receptacle 72 disposed at a position lower than the base 50 on one side of the base, an upper receptacle 74 disposed at a position higher than the base 50 on another side of the base, and a transfer means 76 for transferring the elongated stock 66 from the lower receptacle 72 to the upper receptacle 74.
The method for drawing the elongated stock members 66 with use of the elongated stock drawing apparatus will now be described. As shown in FIGS. 13, 14, and 15, a predetermined number (three in FIG. 13) of the elongated stock members 66 are put on the holder 68 which is in an inclined state. In this case, the elongated stock members 66 are put on the holder 68 in such a manner that the flat portion 70 thereof and a cylindrical opening thereof are positioned up and down, respectively. The swing means 62 has rods 60 in a number corresponding to the number of the elongated stock members 66. The swing means 62 adjusts the angle of each rod 60 so that the rods are aligned with the elongated stock members 66 on the holder 68. That is, the position of the plug 58 at the front end of each rod 60 is lifted higher than its horizontal position.
Next, a drive means (not shown) provided at an upper end of the holder 68 is driven to move an elongated stock member 66 downward with the cylindrical opening facing down and to receive, through its open end, the plug 58 on the front end of the rod. Thereafter, as shown in FIGS. 13 and 15, the swing means 62 causes the rod 60 to swing into a horizontal position so that a central axis of the rod 60 and the center of the die 52 are aligned with each other. Then, the hydraulic cylinder 64 is actuated to move the elongated stock member 66 toward the die 52 until the flat portion 70 of the elongated stock passes through the interior space of the die 52 and projects from the opposite side. At the same time, the first moving means 56 equipped with the chuck 54 moves toward the die 52 and the chuck 54 chucks the flat portion 70 of the elongated stock 66. In this chucked state of the elongated stock 66, the first moving means 56 moves to the side opposite the die 52. As a result, the elongated stock member 66 passes through the die 52 and is thereby drawn into a predetermined diameter. The elongated stock member 66 thus drawn is received into the lower receptacle 72 as shown in FIG. 14.
For drawing the elongated stock member 66 into a desired diameter, the stock 66 is subjected to a first drawing to a diameter a little larger than the desired diameter and is then subjected to a second drawing to the desired diameter which is relatively smaller. As the case may be, the elongated stock 66 is passed a total of three times or more through dies 52 of different diameters.
Since the elongated stock 66 is long and the lower and upper receptacles 72, 74 are provided to the side of the elongated stock drawing apparatus, the area occupied by the drawing apparatus is large. For this reason, all of the working steps from the beginning to end are carried out using a single elongated stock drawing apparatus. For obtaining an elongated stock 66 of a desired diameter with use of a single elongated stock drawing apparatus, it is necessary that the die 52 and plug 58 used in the first drawing be replaced with smaller ones at the time of shift to the second drawing. This replacement work requires much time and a large number of working steps. The working steps before and after the die and plug replacement have already been automated, but the attainment of complete automation throughout requires automation of this replacing work.
In drawing, the distance X (FIG. 15) between a front-end position of the plug 58 inserted into the die 52 and an outlet position of the die 52 is very important in attaining high drawing accuracy and it is necessary to adjust the distance X with every replacement of the plug 34. The distance X is visually checked. For checking the distance X with this apparatus, a worker is required to position his or her head in a region (region Y in FIG. 15) on the side opposite the rod 60 in the die 52 and to check the distance X visually. However, the holder 68 is an obstacle to positioning of the worker""s head in region Y and thus it is difficult to visually check and adjust the distance X.
The present invention has been accomplished in view of the above and it is an object of the invention to provide a continuous drawing method and apparatus for an elongated stock member which permit plural types of drawings to be carried out, in an area narrower than that of the prior art, by a series of automated steps and which permit easy adjustment of the distance between the front-end position of the plug and the outlet position of the die.
For achieving the above-mentioned object, the continuous drawing method according to the present invention comprises providing a movable die holding member, with plural different types of dies being mounted at a central position relative to reciprocation of the elongated stock members, and with a large opening allowing the stock members to bypass the dies when moved from one side to the opposite side of the die holding member. The die holding member can also be positioned to allow the elongated stock members to be drawn through one set of the plural dies when the elongated stock is to be moved from one side to the other of the die holding member, causing the elongated stock to reciprocate plural times between the one side and the opposite side with the die holding member therebetween, and moving the die holding member at every passage of the elongated stock through one of the die sets to change the die type from one to another.
For achieving the foregoing object, the continuous drawing apparatus according to the present invention comprises a base, a die holding member movable with respect to the base and having plural different types of dies attached thereto, a chuck means for chucking the elongated stock, a first moving means for moving the chuck means toward the die holding member; the first moving means being provided on one side of the die holding member, a rod to be inserted into the elongated stock provided on the side opposite the first moving means with respect to the die holding member, and a second moving means for moving the rod toward the first moving means, whereby when the elongated stock member is moved to the rod side by the first moving means and is fitted on the rod, the elongated stock is passed through a space in the die holding member bypassing the dies. Then, when the elongated stock fitted on the rod is moved toward the first moving means by the second moving means, the die holding member is moved so that the elongated stock is drawn through one of the dies.